In this study, we compared the soil characteristics of areas of forest and pasture areas, considering four different ages
installation at three sites in the state of Rondonia. The sites were chosen with the aid of sensor images TM / Landsat, obtained between 1987 and 1997, and two in Acrisol (PVA) and in a Chromic Luvisol (CT).
Soil samples were collected in the layer of soil to 20 cm and subjected to analysis fertility and grain size, obtaining data for pH, exchangeable bases, available phosphorus, aluminum saturation and bases and organic carbon. To
dystrophic soil and low fertility (PVA), the addition of gray from the burning of forest and crop residues in the first year of
implementation of grazing have greatly influenced the dynamics of soil. For two sites of PVA, the level of saturation remained higher in the pasture, even though more than 10 years old, found in the area forest. While aluminum showed low level after the implementation of grazing all age groups studied. Available phosphorus was down fast after reaching the peak value and after a period of more than 10 years of use with pasture, showed a value almost equal to the original in the two types of
soil studied. In the case of eutrophic soil (CT), the effect of gray, in general, was lower intensity compared to the dystrophic soil (PVA), showing high loss of nutrients over time, due to factors associated with low clay content soil and the more pronounced local relief.